A self-service register (self-service checkout POS or self-service checkout apparatus) carries out registration and transaction settlement with respect to a commodity through an operation by a customer (user) who purchases the commodity. For example, in a large retail store, both the self-service register and a registration apparatus operated by a store clerk are installed together in many cases. In such an application, it is desired to provide an apparatus capable of reducing a burden on the customer in order to improve a usage ratio of the self-service register. On the other hand, a conventional self-service register is provided with a function (weight check process) of checking weight so as to detect presence of an unregistered commodity or the like. In the weight check process, it is determined whether a difference between weight of registered commodities and weight on a placement table on which a shopping bag containing the registered commodities is set is within an allowable range. If it is determined that the difference therebetween is beyond the allowable range, the self-service register displays an error message and stops registration of the commodities.
The conventional self-service register carries out the weight check process on the assumption that a commodity is packed in a shopping bag after the customer completes registration of the commodity. Therefore, if the commodity is packed in the shopping bag before the commodity is registered, the conventional self-service register displays an error notification or the like to instruct the customer to take out the unregistered commodity, and thus, the registration of the commodity cannot be completed.
However, in an actual application, it may be necessary to perform a key operation to register a commodity temporarily held by the customer. In such a situation, the customer needs to perform the key operation with one hand while holding the commodity with the other hand, or to temporarily put the commodity at a place other than the shopping bag and then perform the key operation. In the conventional self-service register, even if the key operation needs to be performed, it may not be possible to place a commodity in the shopping bag until the registration of the commodity is completed, thereby reducing work efficiency. As the reduction of the work efficiency causes a stress to the customer, there is a problem that the usage ratio of the self-service register is reduced accordingly.